This is because SRB2 also has a TEXTURE2 lump for adding custom resources (so PWADs have no need for a TEXTURE1 lump). That means I have to rename TEXTURE2 back to TEXTURE1, add my custom patches, then rename it back to TEXTURE2. And that's every time I want to change something, which is a bit of a pain in the arse.

Here's SRB2's palette for inclusion if you do opt to add support for it.